armcclure

iTrader: (2)

I snapped the one on the head. When I pull the cover ill document all of the bolts. I jave a ised replacement coming from mrb. Thanks though.

c130aviator

iTrader: (8)

thats another bolt that I see snapping often. At the very least that bolt and the guide bolt should be upgraded for sure. I am going to pull that bolt behind the plug on the head and replace it with a grade 10.9 tomorrow. Before it breaks. SHM.

Tjolley

That bolt has a 10.5mm sholder on it.
Im replacing every bolt with ARP and going to 8mm bolts

JapEatr

iTrader: (9)

Does ARP make shoulder bolts?

Tjolley

Not that i know of but caterpillar does. Lol free for me

Tjolley

Im also changing the cam hold down bolts to ARP M6x1.0x40mm

Powell Race Parts

iTrader: (3)

at 89 inch pounds torqueing or in service? bolts should be changed with tensioner and guides and oiler and sprockets in a rebuild....they are weak, but if you make the bolt stronger, you risk making another part weaker...so its a puzzle for sure...

mrbelvedere

iTrader: (3)

you cant get a code for intake cam correlation that code is for exhaust only

there is a half a thousands interference fit with the ati the looser the fit the less it works as for stock dampener operation you cant tell by feel if the stock dampener is working or not at 7500 the stock dampener after 6500 dose jack for help

you machine the hub of the dampener not the crank as stated above and extending the key way would also be benificial

mrbelvedere

iTrader: (3)

as for the replacement the hardness of the stock bolt is fine and dandy and using a harder grade bolt can be a downfall as they can be brittle from the process of hardening the iseal fix is a bigger diameter bolt with the same hardness as stock

c130aviator

iTrader: (8)

They make a shoulder bolt in the higher grade if you want to buy it online. I didnt care and it was cheaper locally. I used a 10.5mm exact fit washer behind the new bolt so all is well. I have jars and jars of washers so I found one that was perfect. But anyway its not going to affect anything, other than its not called an automotive bolt, LOL

I for one am very happy that all my timing area issues are fixed and stronger. The fact that our tensioners allow so much slap with 82 # or greater valve springs can really beat on those bolts and guides. Only makes sense to upgrade them. In fact I am surprised this hasnt been done before or added to some thread for cheap insurance/upgrades. But it has to be super popular or everyone has to have it for this board to really take notice of a good idea.

Powell, I was thinking stock engine parts are great with the 9.8 bolts but when you upgrade, everything under the valve cover needs to be looked at for weakness. This is the next logical thing when there are so many out there breaking bolts...

Powell Race Parts

iTrader: (3)

I dont believe that the timing chain is that bad, in fact ZZP say the chain lasts forever. But rigorous maintenance schedules are necessary if you are not stock . If you are stock, regular oil changes and an updated tensioner will do the job for most people.

the failure mode seems to go like this: rev the crap out of the engine with stock springs/ need tensioner/dont replace it right away /continue to rev the crap out of the engine/replace the tensionser/continue etc/ break black chain guide pieces/ dont know dont look/break guide bolt/ start looking etc.

If you mod your car and rev the crap out of it, 40,000 miles is a dream for durability.
so the question is, when rebuilding your engine, did you replace the entire front chain /sprocket/tensioner/ upgraded oilers and guides etc at that time? You should.

My guess if you do, and use a torque wrench , its only in extreme builds you need to consider better fasteners and if that were the case, I would do larger diameter ones like Mr. B suggests.

armcclure

iTrader: (2)

Mine snapped "in service" it had been on for about a year. Wasn't even racing or anything, just cruising back from a meet and heard it rattling at a drive through window.
My car has seen high rpm several times though. Could very well have cracked/damaged the bolt at some point and it just decided to finally let go pulling into Taco Bell.

c130aviator

iTrader: (8)

I will say that anyone that takes notice of the timing, know that it was well thought out. When components break you can tell pretty much right away, as Armcclure had heard, when I heard mine, I did not beat on it, etc... So then you pull the oil pump timing cover, it is designed so that when a component fails it rests against the cover not allowing the bolts to fly off and run loose in the housing or in the oil pan, etc. There is fail safes there as I had demonstrated before when the guide is relieved of pressure it rests against the crank gear so that the chain doesnt slip time. Very innovative. The engine in our cars is well designed. Wish I could say the same for our chassis.

So while a larger bolt would be ideal the hole in the guides would need to be enlarged and reengineered. The problem is the black guide is oval shaped and doesnt allow for a larger bolt, you hack it up it wont work. The guide on the chain, the aluminum one needs re-engineered as well, its a slip type washer built in, you enlarge it you remove this piviot point making the bolt the pivot point. YOu then wear the bolt down and still have the problem.

I feel this is the best and easiest way to strengthen ever so slightly a reoccurring problem with these bolts. But I will let you know if I have any further issues since I post just about everything I do to my car.

mrbelvedere

iTrader: (3)

you don't need to reengineer the chain guides to but bigger hardware in place you just need to be 2% smarter then the part your going to modify if you look the bolt that broke in your engine is the easiest to mod and put bigger bolt in and as for the bolts breaking and not falling into the pan is false they will there have been a few on here that has had that happen

armcclure

iTrader: (2)

Another thing to remember; just because a bolt is stronger doesn't necessarily mean its harder... There are tons of options out there besides the 2 grades mentioned in here.

c130aviator

iTrader: (8)

I have another guide laying here, the next metric bolt wont fit, so there went my 2% on that part. It super easy to engineer stuff when all you have to do is type it from your keyboard, execution is the hard part.

Exactly, making a bolt a higher grade doesnt mean its brittle, the alloys could be many different things so just assuming hardening is the only thing done is to assume some people didnt look into what makes a bolt a different grade all together.

mrbelvedere

iTrader: (3)

execution is the easier part of it all you just need a drill bit and a tap to do the job

c130aviator

iTrader: (8)

Just thought I would throw an update out there. 6 weeks revving the crap out of the new motor/bolts and no more timing issues/noise.

574

iTrader: (5)

Pretty sure I got new guide bolts in my deluxe timing kit, do you know if those are 10.9? Or are they same as stock?

c130aviator

iTrader: (8)

they are 9.8